Semiconductor fabrication generally involves numerous sophisticated and complex processing steps. Monitoring and evaluation of each process step is crucial to ensure the manufacturing accuracy and to ultimately achieve the desired performance of a finished device. Throughout numerous processes, such as the imaging process, deposition and growth process, etching and masking process, it is critical, for example, that temperature, gas flow, vacuum pressure, chemical gas or plasma composition and exposure distance be carefully controlled during each step. Careful attention to the various processing conditions involved in each step is a requirement of optimal semiconductor or thin film processes. Any deviation from optimal processing conditions may cause the ensuing integrated circuit or device to perform at a substandard level or, worse yet, fail completely. Processing conditions include parameters used to control semiconductor or other device manufacture or conditions a manufacturer would desire to monitor.
Within a processing chamber, processing conditions can vary. The variations in processing conditions such as temperature, gas flow rate and/or gas composition greatly affect the formation and thus the performance of the integrated circuit. Using a substrate-like device to measure the processing conditions that is of the same or similar material as the integrated circuit or other device provides the most accurate measure of the conditions because the thermal conductivity of the substrate is the same as the actual circuits that will be processed. Gradients and variations exist throughout the chamber for virtually all process conditions. These gradients therefore also exist across the surface of a substrate. In order to precisely control processing conditions at the substrate, it is critical that measurements be taken upon the substrate and that the readings are available to an automated control system or operator so that the optimization of the chamber processing conditions can be readily achieved.
In recent years, low profile wireless measuring devices have been developed. They are typically mounted on the substrate to measure the processing conditions. For a low profile wireless measuring device to work in a high temperature environment (e.g., temperatures greater than about 150° C.), certain key components of the device, such as thin batteries and microprocessors, must be able to function when the device is exposed to the high temperature environment. In general, the back AR coating (BARC) process operates at 250° C.; a CVD process may operate at a temperature of about 500° C.; and a PVD process may operate at about 300° C. Unfortunately, batteries and microprocessors suitable for being used with the measuring devices cannot withstand temperature above 150° C. While wired measuring device may measure temperatures higher than 150° C., they are not preferred because they are cumbersome and require a long downtime associated with a measurement.
In order to make wireless measuring devices work at temperatures higher than 150° C., low profile heat shield modules have been proposed for protection of temperature sensitive components (i.e., CPU, battery) of the measuring device. These modules are typically attached to the wafer substrate. Some methods have been proposed in associated with attachment of the module to the wafer substrate.
One example of conventional mounting of a heat shield module is shown in FIG. 5. The module (not shown) may be conventionally attached to a substrate 101 by inserting one or more rivet shaped pins 102 in a respective recessed cavity 103, called a T-slot, in the substrate. In particular, a rivet-shaped pin 102 is inserted in a T-slot, and the remainder of the cavity 103 is filled with a suitable adhesive such as epoxy or polyimide. With this method, the wafer has to be grinded, and introduction of micro-cracks during a grinding process would weaken the wafer. Also, sliding the rivet pin into the T-slot may cause the lip of the T-slot to fracture. Additionally, the T-slot may break if the height of the rivet pin head is slightly taller than the T-slot height or if all of the rivet pins do not fall on exactly the same plane.
It is within this context that embodiments of the present invention arise.